Floating Menus become trasparent when click it on mobile post

Hello.
My website is https://www.ivisitkorea.com
I applied floating menus and it works well on desktop browsers.
But on mobile, it becomes transparent when I click it on the post.
It has a white background only on the mobile homepage.

I added additional CSS as below.

a {
color: #ee9e03;
}

#site-header-right-menu {
display: none;
}

#site-header-right-menu .search-form {
display:none;
}

Thank you for your help in advance.

Kindest regards,
Jay Han